Recently, the so-called shoe press for dewatering a wet web by pressing one surface of the wet web disposed on a felt travelling fast with a press roll and pressuring the other surface with a pressure shoe with an endless belt interposed therebetween is widely used in a press part of a paper-making process, in order to increase an efficiency in dewatering the wet web. The shoe press has conventionally used a belt formed in an endless manner with a reinforcing substrate integrated with an elastic material such as thermosetting polyurethane.
As shown in FIG. 11, a typical structure of the shoe press belt has elastic materials 102, 103 formed on the opposite surfaces of a base fabric 101, and also has a surface provided with a groove 104 in order to improve the dewatering ability.
In the shoe press, severe flex and pressure repeatedly applied on the belt between the press roll and the pressure shoe may cause cracks from the exterior peripheral surface of the belt in course of using the belt. Once the cracks occur, they grow bigger with the use of the belt. The growing cracks cause lubricating oil between the interior peripheral surface of the belt and the pressure shoe to leak outside to adversely affect the web, or cause delamination of the belt.
To solve the problem described above, Japanese Patent Laying-Open No. 11-12975 discloses a shoe press belt where a concave groove at an outer region of a width of a belt has a depth shallower than a concave groove at an inner region of the width in order to improve the crack-resistance in the vicinity of the shoe edge portion. However, even though the groove in the vicinity of the shoe edge portion has a depth shallower than the groove at the inner region of the width, the crack-resistance cannot be improved and cracks may be caused or grown.